Field of the Invention
The present invention relates to a zoom lens for projection and a projection-type display apparatus. For example, the present invention relates to a zoom lens for projection appropriate to magnify and project an original image formed by a light valve or valves onto a screen and a projection-type display apparatus using the zoom lens for projection.
Description of the Related Art
Conventionally, projection-type display apparatuses that magnify and project images displayed on light valves, such as a liquid crystal display device, have been widely used. A cross dichroic prism is ordinarily used to combine colors in an optical system using transmission-type liquid crystal display devices, as light valves. Therefore, a lens for projection used in the optical system is made telecentric toward a reduction side to improve the color combination characteristics of the cross dichroic prism by taking the angle dependence characteristics of the cross dichroic prism into consideration.
When a projection-type display apparatus is used for presentation, projection in large screen size with a short projection distance is often required in a space with a relatively narrow distance from the front to the back of the space. Therefore, a demand for a wide angle lens, as a projection lens, is strong. In a wide angle lens, a change in screen size relative to a change in projection distance is large, compared with a lens with a small angle of view. Therefore, in some cases, the screen size is adjustable by changing a distance from the set apparatus to a screen only a little. However, the flexibility of the setting condition is often extremely small because the distance from the front to the back of the space is limited, as described above. Therefore, there is a tendency to prefer a zoom lens adjustable to a desirable screen size even if a distance from the set apparatus to the screen is limited.
For example, a zoom lens for projection disclosed in Japanese Unexamined Patent Publication No. 2010-237605 (Patent Document 1) is known, as a zoom lens for projection having a wide angle of view, and which is configured to be telecentric toward a reduction side. Patent Document 1 discloses a lens system consisting of five groups, in which a negative first lens group, a positive second lens group, a negative third lens group, a positive fourth lens group, and a positive fifth lens group are arranged in this order from a magnification side.